BugMD Flea & Tick Concentrate Works instantly. I spray it on the brush or on the dog. My puppy can't tolerate fleas crawling on her, so BugMD has been a game changer for Sofi. We also have cats. One is feral, so he goes outside everyday. Therefore, he is bringing fleas into the house everyday & wants to sleep in bed with the family. I spray all the bedding once daily. I see immediate results with this flea & tick concentrate.